1. Field of the Invention
The present invention relates to a stencil printing apparatus with a plate-making device.
2. Description of the Related Art
As a simple printing system, there is known a digital heat-sensitive stencil printing apparatus (called “stencil printing apparatus” hereinafter) equipped with a digital heat-sensitive plate-making device. In this plate-making device, a thermal head having a plurality of heat generators, referred to as heat generating elements or heat generating resistors, arranged in a main scanning direction and a platen roller are used to press a heat-sensitive stencil master (simply called “master” hereinafter) having a thermoplastic resin film (simply called “film” hereinafter), and in the meantime the master is relatively moved in a sub-scanning direction perpendicular to the main scanning direction, by rotating the platen roller, and then a perforated/plate-making image with dots (perforated pattern) is formed on the master by means of the heat generated by each of the heat generators of the thermal head in response to an image signal.
In a general stencil printing apparatus, after the engraved master on which the perforated/plate-making image is formed using the plate-making device as described above is wound around the outer periphery of a plate cylinder, the plate cylinder is rotated to convey a print sheet, which is a medium to be printed (simply called “sheet” hereinafter), to the space between the plate cylinder and a pressing member such as a press roller or an impression cylinder at predetermined timing in synchronization with the rotational movement of the plate cylinder. Then, the pressing member pressure-welds the sheet to the engraved master on the plate cylinder, and ink supplied into the plate cylinder is caused to bleed from an opening portion of the plate cylinder, a mesh screen and a perforated portion of the master and then shifted/transferred to the sheet, whereby the sheet is obtained as a printed matter.
Thereafter, the printed matter with the transferred plate-making image is delivered to a sheet delivery table and stacked sequentially thereon. The ink used in the general stencil printing apparatus is emulsion ink, which cannot be fixed immediately after transferred to the sheet. The printed matter is normally dried naturally, i.e., as the ink is absorbed into the sheet over time. In other words, the printed matter is dried naturally. Specifically, if regular print ink is used when executing stencil printing, the ink is infiltrated and dried, causing offset and bleeding, and thus it is generally difficult to obtain a good double-sided printed matter using the regular ink. Moreover, the regular ink is not dried easily on art paper or coated sheet with a shiny surface, hence, even when single-side printing is performed, it is difficult to obtain a good single-sided printed matter.
Therefore, there is proposed an apparatus for performing double-side printing using a stencil or stencil printing on art sheet or coated sheet by using photo-curable ink (ultraviolet light) which is active energy ray curable ink, and light (ultraviolet light) irradiation means, which is active energy ray irradiation means (see Japanese Published Unexamined Patent Application No. 2004-136672 and Japanese Published Unexamined Patent Application No. 2006-281658, for example).
However, use of active energy ray curable ink and printing on coated sheet are not taken into consideration in the general stencil printing apparatus, because printing using both the active energy ray curable ink and coated sheet has problems of printing wrinkles and master wrinkles that cause image defects such as white stripes generated due to floating of an engraved master.